The secretion of mucus is a major determinant of both morbidity and mortality in asthma and other respiratory diseases. In order to examine mucus secretion, culture of respiratory tissues secreting biosynthetically-labeled mucus glycoproteins has been examined. Anaphylaxis of airway or nasal mucosa leads to mucus release and the production of 5-HETE 12-HETE and 15-HETE. Each of those HETE's is a mucus secretagogue as are SRS-A, histamine, cholinergic and alpha-adrenergic agonists, several prostaglandins and cyclic GMP. Prostaglandin-generating factor of anaphylaxis (PGF-A) also generates both mucus and HETE formation and may contribute to the mucus production seen in anaphylaxis. Phagocytosis of particles by macrophages leads to the elaboration of a low molecular weight, non-lipid material which is a potent stimulator of mucus secretion, which has been termed macrophage mucus-secretagogue (MMS). MMS release is seen from pulmonary alveolar macrophages as well as peripheral monocytes in response to zymosan ingestion or Staph protein A interactions. Mucus secretions from nasal and airway mucosa is inhibited by both corticosteroids and tetracycline. The combination of these agents acts in an additive fashion and has direct therapeutic implications.